Roche's Tamiflu - Is It Or Isn't It Effective?

1/23/2012 12:21 PM ET

Come winter and there is a surge of flu cases. Influenza, commonly referred to as flu, is an acute and contagious viral infection of the respiratory tract. Nearly 3 million to 5 million cases of seasonal influenza occur every year, and around 250,000 to 500,000 people are dying from this disease, according to the World Health Organization, or WHO.

The most commonly prescribed anti-viral medication for influenza is Oseltamivir sold under the brand name Tamiflu by Swiss drug giant Roche Holding AG (RHHBY.PK). Tamiflu, which belongs to a class of medications called neuraminidase inhibitors, is also recommended for prevention and treatment of swine flu and bird flu.

As a pandemic preparedness policy, governments and health agencies across the world stockpile antiviral flu drugs and vaccines, spending billions of dollars. Amid this backdrop, Tamiflu is not only the major flu drug that is stockpiled but is also on the list of WHO essential drugs.

While on one hand, Tamiflu is stockpiled globally as a defense against pandemic influenza, on the other hand, doubts are being raised over the efficacy of this medical arsenal against flu.

According to a new report by The Cochrane Collaboration, which reviewed the randomized controlled trial evidence of neuraminidase inhibitors like Tamiflu in treating and preventing influenza, there is a high risk of publication and reporting biases in the trial program of Tamiflu.

The Cochrane Collaboration is an international not-for-profit organization preparing, maintaining and promoting the accessibility of systematic reviews of the effects of health care.

The authors conducting the review said that they have been unable to obtain the full set of clinical study reports or obtain verification of data from Roche, the manufacturer of Tamiflu, despite five requests between June 2010 and February 2011.

The review by the Cochrane group found that Tamiflu shortens duration of symptoms by less than a day in people with influenza-like illness but there is no evidence of an effect on hospitalizations. Moreover, conclusions regarding efficacy outcomes namely, viral transmission and complications of influenza, associated with Tamiflu were hard to determine. Pneumonia, ear infections, sinus infections and bronchitis are some common complications of influenza.

The authors of Cochrane reviews have concluded that the quality of the trials poses significant challenges to drawing meaningful inferences about the effect of Tamiflu on complications of influenza.

Full clinical study reports are needed to draw conclusions about Tamiflu's effect on complications or transmission of influenza, according to the new report by the Cochrane group.

However, Roche, which has been accused of withholding full data related to Tamiflu trials, reportedly said in a statement that it provided the Cochrane group with access to detailed information running to 3,200 pages and that the full study data had been made available to regulatory authorities.

Refuting aspersions cast on Tamiflu's efficacy, Roche reportedly added that "numerous clinical trials and real-life medical experience show Tamiflu is effective in reducing the severity and duration of influenza symptoms as well as specified secondary complications".

Tamiflu has been in use since 1999 when it was approved in the U.S. and Switzerland. The drug was approved throughout the European Union in 2002.

In 2009, global sales of Tamiflu rose 400% to 3.2 billion Swiss francs, following the pandemic swine flu outbreak. But the following year - in 2010, sales of the drug dropped to 873 million Swiss francs, and in the first nine months of 2011, sales were 301 million Swiss francs, down by 57% compared to the year-ago period.

Tamiflu was invented by Gilead Sciences Inc. (GILD) and licensed to Roche in 1996. The drug has patent protection until 2016.